Jordanian authorities are tightening security, as investigators hunt for the masterminds of three suicide bombings at Western-owned hotels in the capital, Amman. Al-Qaida in Iraq has claimed responsibility for the blasts, which killed at least 56 people and wounded more than 100 others.

Almost immediately after the suicide attacks, authorities said they bore the hallmarks of Jordanian-born terrorist Abu Musab al-Zarqawi. Thursday, those suspicions appeared to be confirmed, when Zarqawi's group, al-Qaida in Iraq, claimed responsibility through an Internet posting.

The statement said Amman is what it called the “backyard garden for Jews and U.S. crusaders” in Iraq. Although the claim could not be immediately verified, Jordan's Deputy Prime Minister, Marwan Muasher, said Zarqawi is a prime suspect.

"This is a terrible event. It only shows how dangerous and volatile the area is, and how much we all have to be dedicated to fighting terror and in taking the necessary measures in order to stop it."

Although Abu Musab al-Zarqawi is best known for suicide attacks in Iraq, largely targeting U.S. troops, he has been equally active in Jordan, whose Hashemite monarchy he detests.

His group is accused of trying to blow up the Amman Radisson once before, as part of 1999’s "Millennium Plot," and is blamed for last August's attack on a U.S. Navy ship in Aqaba. Zarqawi was also sentenced to death in absentia by a Jordanian military court for the 2002 assassination of U.S. diplomat Laurence Foley in Amman.

Thursday, Jordan's King Abdullah the Second cut short his visit to Kazakhstan, returning to Amman to survey the damage and convene a meeting of his security chiefs.

Hundreds of angry Jordanians rallied outside one of the targeted hotels, raising their voices against their countryman, Abu Musab al-Zarqawi.